Comparative Assessment of Cephalometric and Tympanometric ...

Received 08/15/2018 Review began 08/19/2018 Review ended 09/11/2018 Published 09/13/2018

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Comparative Assessment of Cephalometric andTympanometric Readings in Down SyndromeSunali Khanna , Prita A. Dhaimade , Rangasayee Raghunathrao

1. Municipal Corporation of Greater Mumbai, Nair Hospital Dental College, Mumbai, IND 2. Oral and MaxillofacialSurgery, Cooper Hospital, Mumbai, IND 3. Hearing and Speech Sciences, Dr. S. R. Chandrasekhar Institute of Speechand Hearing, Bengaluru, IND

Corresponding author: Sunali Khanna, [email protected]

AbstractAim The purpose of this study was to conduct a comparative assessment of the various cephalometric andauditory parameters between patients with Down syndrome (DS) and healthy controls.

MethodsThe cephalometric and auditory parameters were divided among 50 participants into two equal sets, DS (n =25) and controls (n=25), and assessed. While a standard cephalometric analysis was conducted to measurethe hard tissue parameters, tympanometry was used to assess the audiological parameters.

ResultsThe values of the linear and angular cephalometric parameters of the DS group were found to be lower thanthe controls. All the controls recorded type A tympanogram while the DS group recorded type A, B, and Ctympanograms. A significant relationship was observed in the cephalometric readings – eustachian tube(ET) length, posterior upper facial height (PUFH) length, sella (s)-basion (ba)-palatal length (PL), and s-ba-ET angles – among the subjects who presented with type B or C tympanogram in comparison to those withtype A.

Conclusion Tympanometry, a highly sensitive and relatively simple test to assess audiological parameters, has asignificant relationship with a number of cephalometric indicators of growth and development. A deviationfrom the normal tympanometric readings can be used as an early indicator of the impending craniometricaberrations and handicap. This can be used as an effective tool for early intervention in cases of DS. Patientswho have recorded abnormal tympanograms on multiple occasions over a period of six months can besubjected to a further cephalometric analysis.

Categories: Otolaryngology, RadiologyKeywords: down syndrome, cephalometry

IntroductionDown syndrome (DS) is the most common genetic cause of moderate intellectual disability in children [1]. Itwas first described by John Langdon Down, a British physician, in 1866. The incidence of DS is seen to be ashigh as one in every 800-1200 births, irrespective of race and inheritance. Genetically, it can occur as aresult of mosaicism, translocation, and, most commonly, trisomy 21 (95%). In trisomy 21, the zygotecontains three copies of chromosome 21, causing every cell to have 47 chromosomes. One of the major riskfactors for this non-disjunction to occur is increasing maternal age [1]. DS has been associated with anumber of pathological abnormalities, primarily of the craniofacial region, including brachycephaly, reducedoral fissure, dental abnormalities, macroglossia, flat nasal bridge, etc., and several audiologicaldeficiencies [2].

With the evolution of modern medicine, the average life expectancy of a child with DS has increasedsignificantly [3]. With a better understanding of the pathophysiology of this condition, the focus has shiftedfrom merely increasing life expectancy to providing a better quality of life to a child with DS [3]. A number ofstudies have explored the relationship between a child’s audiological abilities and normal craniofacial andintellectual development along with the importance of early intervention [4]. Language and speechdevelopment occurs in children primarily before the age of five years, and any impairment in this can lead tomultiple, long-term developmental disabilities. The otolaryngologic and audiological impairments in DS arenot uncommon and hence create a potential of additional disability [5]. Many anomalies of the pinna andmiddle ear have been noted in DS along with hypoplasia of the epitympanum and the round window,

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Open Access OriginalArticle DOI: 10.7759/cureus.3301

How to cite this articleKhanna S, Dhaimade P A, Raghunathrao R (September 13, 2018) Comparative Assessment of Cephalometric and Tympanometric Readings inDown Syndrome. Cureus 10(9): e3301. DOI 10.7759/cureus.3301

ossicular abnormalities and, most importantly, structural abnormalities of the eustachian tube (ET) [5]. Theacute angle of entry into the nasopharynx, along with the diminished tube size classically seen in DSpredispose the patient to recurrent infections of the middle ear, ultimately increasing the risk of chronicotitis media. The incidence of chronic otitis media was found to be significantly higher in DS (39% to 89%)than in the general population (2.5%) [6-7].

Cephalograms and cephalometric analyses have been used as the standard measures of craniofacial growthand development. Along with orthodontic and skeletal growth analysis, lateral cephalograms are oftenemployed to calculate various cranial parameters, such as ET length, total cranial base (TCB), posteriorupper facial height (PUFH), maxillary depth (MD), etc. The calculation/monitoring of the audiologicalparameters and the middle ear status can be conducted in a non-invasive way using tympanometry and puretone audiometry [8].

Early identification and intervention coupled with a regular re-evaluation of the audiological parametersbefore the onset of chronic otitis media can help reduce the severity of disability in the risk groups [9]. Amulti-disciplinary approach must be adopted, which involves a dentist, an otolaryngologist, a speechtherapist, etc., along with the consulting pediatrician, to improve the social and cognitive function ofchildren with DS, thus ensuring a bridging of the gap toward a normal life [7]. The aim of this study was toassess and explore the relationship between the cephalometric and audiological parameters of patients withDS and healthy controls.

Materials And MethodsA randomized convenience sampling technique was utilized for sample size determination. A total of 50subjects were selected from the age group of seven to 20 years. Approval from the institutional ethicalcommittee was obtained along with informed consent from all subjects and/or guardians prior to thecommencement of the study.

The subjects were divided into two groups: DS (n = 25; determined using genotyping records) and healthycontrols (n = 25).

Digital lateral cephalometry was carried out identically among all the subjects. They were exposed in an erectposition with teeth occluded, lips in response, and head stabilized with a cephalostat. Radiation protectionparameters were adhered to. Cephalometric tracing was carried out manually. Linear and angularmeasurements were recorded and tabulated.

The craniofacial landmarks included were the following (Figure 1):

a. Linear measurements

i. ET length (mep-pt)

ii. TCB (nasion (n)-basion (ba))

iii. PUFH (sella (s)-posterior nasal spine (pns))

iv. MD ((anterior nasal spine (ans)-(pns))

b. Angular measurements

i. s-ba to palatal line (PL)

ii. s-ba to ET length

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FIGURE 1: Cephalometric landmarks, linear and angular measurementss: sella, ba: basion, n: nasion, pns: posterior nasal spine, ans: anterior nasal spine, PL: palatal line

Tympanometry was the tool used to assess the audiological parameters among both groups. Further, bothgroups were subjected to ENT and audiological examinations were conducted by the Rehabilitation Councilof India-certified audiologists. These tests were conducted in standard audiometric sound-treated roomsusing standardized equipment calibrated as per the American National Standards Institute (ANSI): S3.6 -1996 specifications or the Bureau of Indian Standards (BIS) specifications IS 10565:1999 (R 2005) fordiagnostic audiometers. The data were subjected to statistical analyses using Microsoft Office Excel(Microsoft Corporation, Redmond, WA, USA) and Statistical Package for Social Sciences (SPSS, IBM Corp.,Armonk, NY, US) software. The confidence level chosen was 95%. The analysis of variance (ANOVA) test wasused for a statistical analysis.

ResultsStandard cephalograms were recorded for both the controls and the DS group, followed by accuratecephalometric tracing and documentation of the readings. Figures 2-3 show a graphical representation of thelinear and angular cephalometric readings of the controls and the DS group.

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FIGURE 2: Comparison of linear cephalometric parameters among DSand controlsET: eustachian tube, TCB: total cranial base, PMH: posterior maxillary height, MD: maxillary depth, DS: Downsyndrome

FIGURE 3: Comparison of angular cephalometric measurements amongDS and controlss: sella, ba: basion, PL: palatal line, ET: eustachian tube, DS: Down syndrome

All controls presented with a 'type A' tympanogram while the DS group presented with 'type A, B, and C'tympanogram readings, as seen in Figure 4 and Table 1. When comparing A, B and C, the ‘p-value’ was foundsignificant for two of the linear parameters, i.e., ET length and PUFH length, and both angular parameters,i.e., s-ba to PL and s-ba to ET length. Tables 2-5 represent statistical calculations for the same.

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FIGURE 4: Tympanometric assessment of the DS group and the controlsDS: Down syndrome

TympanogramControl Down

TotalN % N %

A 25 100 12 48 37

B 0 0 8 32 8

C 0 0 5 20 5

Total 25 100 25 100 50

TABLE 1: Tympanometric assesment in DS and controls

Tympanogram NET length

One-way ANOVAMin Median Max Mean SD

A 37 31 40 51 39.65 4.608

P = 0.0426, significant differenceB 8 31 35.5 40 35.63 2.504

C 5 30 36 44 36.6 5.079

TABLE 2: Comparison of ET length and tympanograms in the DS groupET: eustachian tube, DS: Down syndrome, ANOVA: analysis of variance

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Tympanogram NPUFH

One-way ANOVAMin Median Max Mean SD

A 37 23 44 58 43.84 6.296

P = 0.0332, Significant DifferenceB 8 35 37 45 38.25 3.576

C 5 38 39 45 40 2.915

TABLE 3: Comparison of PUFH length and tympanograms in the DS groupPUFH: posterior upper facial height, DS: Down syndrome, ANOVA: analysis of variance

Tympanogram Nsba-PL

One-way ANOVAMin Median Max Mean SD

A 37 46 60 70 58.19 6.603

P = 0.0007B 8 42 51.5 56 50.13 4.941

C 5 45 50 53 49.8 2.95

TABLE 4: Comparison of sba-PL angle and tympanograms in the DS groups: sella, ba: basion, PL: palatal line, ANOVA: analysis of variance, DS: Down syndrome

Tympanogram Nsba-ET Length

One-way ANOVAMin Median Max Mean SD

A 37 55 70 85 70.73 5.858

P = 0.0006B 8 51 62 70 62.13 6.312

C 5 57 65 70 64.4 4.879

TABLE 5: Comparison of sba-ET angle and tympanograms in the DS groups: sella, ba: basion, ET: eustachian tube, ANOVA: analysis of variance, DS; Down syndrome

DiscussionDS has a relatively high rate of occurrence among genetic disorders and has some definite risk factors likeincreased maternal age [10]. Karyotyping is the most reliable tool to diagnose DS; an extra chromosome or agenetic material from chromosome 21 can be identified definitively. Although the genetic causes of DS mayvary, i.e., mosaicism, translocation, or trisomy 21, DS shows a multitude of classical craniofacialcharacteristics, such as mongoloid slant, ear abnormalities, epicanthic folds, flat facies and hypotonia [11].An in-depth understanding of these craniofacial and audiological abnormalities is extremely important dueto their high incidence and severity [12]. Early intervention can help reduce the severity of severalcraniofacial abnormalities, such as upper airway obstruction, obstructive sleep apnea syndrome, deafness,speech delay, and otitis media, which frequently occur in these children in later life.

Being a standardized technique in radiography, cephalometry offers valuable information about theintracranial parameters of growth and development. A few such important and radiologically measurablelinear parameters included in this study are ET length, TCB, PUFH, and MD. In normal, healthy adults, theET, also known as the pharyngotympanic tube has two components, a lateral bony portion attached to thetympanic cavity of the middle ear and a fibro-cartilaginous part that extends into the nasopharynx. The ETruns downward, forward, and medially from the middle ear to the nasopharynx [13]. This natural direction

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allows for the ET to function as a dynamic conduit, optimize middle ear sound transmission, and provideprotection to the delicate structures of the middle and inner ear by providing drainage while also equalizingpressure with the nasopharynx [13]. In the past, there have been some reservations regarding the anatomicpoints to measure ET [14]. Previously, the point between the posterior border of the maxilla and the anteriorborder of the PP was considered and not the medial PP that has been recognized as the true localization ofthe nasopharyngeal end of the ET [14-17]. In our study, the ET length was calculated as the distance from‘mep’ to ‘pt.’ The various cranial base parameters like the TCB length have been known to influence anumber of variables, including the growth of the middle ear, facial and mandibular skeletal development,etc. [18]. The growth and development of a normal child lead to cranial growth accompanied by anteriordisplacement of the middle cranial fossa, naso-maxillary complex, and the palatal plane. Hence, PUFH andMD are considered important variables to signify cranial growth and remodeling [18-20]. DS classicallyshows developmental and mental retardation.

In the current study, we observed that the values of all cephalometric measurements in the DS group showeda clear trend to be lower than the values of the normal counterparts (Figures 2-3). To evaluate theaudiological parameters, tympanometry was conducted for the controls and the DS group. Tympanometryhas emerged as a superior tool for the same due to its high degree of sensitivity, total objectivity, andminimal need for subject cooperation [21]. As expected, all the controls were found to have a normal, ie.,type ‘A’ tympanogram (suggests normal middle ear functioning; peak is between +/- 100 daPa; compliancefrom 0.3 to 1.5 ml). The DS group showed type ‘A’ and ‘B’ (suggests middle ear involvement from fluid(middle ear effusion); there is no identifiable peak; ear canal volume is normal) and type ‘C' (suggests ETdysfunction; often seen just before or after effusion; peak is below 100 daPa; compliance from 0.3 to 1.5ml (Figure 4) [22]. Hence, we decided to analyze the data to explore any statistical relation between thecephalometric readings among the subjects who presented with type B or C tympanogram in comparison tothose with A. Here, we were able to identify a significant result (p-value for ANOVA <0.05) from themeasurements of two of the linear parameters, i.e., ET length and PUFH length, and both the angularparameters, i.e., s-ba to PL and s-ba to ET length when comparing A, B, and C (see Tables 2-5). Further, theTukey’s multiple comparison test also detected a 'p-value' significant for the comparison of A and B; hence,there exists a significant difference in the sba-PL angle and the sba-ET angle between individuals havingtype A and B tympanograms.

The reduced values of various cranial base dimensions, i.e., ET length, MD, and PUFH, have been positivelylinked to increased incidences of ear effusion and otitis media previously [23-24]. Since these dimensions areclassically lower in DS, patients with cleft palate and brachycephalic adults, they are much more susceptibleto chronic ear infections that severely diminish the quality of life. [25-26]. However, we recognize that thecurrent study has its limitations, and a larger sample size along with age- and sex-matched controls shouldbe considered in further studies to reduce the number of confounding variables and obtain results that canbe generalizable and applied to a larger population.

ConclusionsThe linear and angular cephalometric readings of the DS group were detected to be less than the normalcontrols. Although the tympanometric readings of the DS group showed considerable variation, we couldidentify a relationship between the tympanometric and cephalometric readings. With the emergingadvances in medicine, the lifespan of patients with DS has increased, but the quality of life can be improvedfurther. Early diagnosis and timely interventions can help identify patients at risk and take appropriatemeasures to minimize the impending handicap. In the future, we can suggest the use of a tympanogram, anon-invasive, early intervention tool, to identify the possible deficiencies in cranial measurements. Patientswho are recorded to have abnormal tympanometric readings over a period of six months can be subjected tofurther investigations like a cephalometric analysis.

Additional InformationDisclosuresHuman subjects: Consent was obtained by all participants in this study. Ali Yavar Jung National Institutefor Hearing and Speech Disabilities issued approval Jan 2010. This research is approved by the Institution ofEthics Committee. Animal subjects: All authors have confirmed that this study did not involve animalsubjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authorsdeclare the following: Payment/services info: All authors have declared that no financial support wasreceived from any organization for the submitted work. Financial relationships: All authors have declaredthat they have no financial relationships at present or within the previous three years with anyorganizations that might have an interest in the submitted work. Other relationships: All authors havedeclared that there are no other relationships or activities that could appear to have influenced thesubmitted work.

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